Signaling of random access preamble sequences in wireless networks

ABSTRACT

Transmission of random access preamble structures within a cellular wireless network is based on the use of cyclic shifted constant amplitude zero autocorrelation (“CAZAC”) sequences to generate the random access preamble signal. A pre-defined set of sequences is arranged in a specific order. Within the predefined set of sequences is an ordered group of sequences that is a proper subset of the pre-defined set of sequences. Within a given cell, up to 64 sequences may need to be signaled. In order to minimize the associated overhead due to signaling multiple sequences, only one logical index is transmitted by a base station serving the cell and a user equipment within the cell derives the subsequent indexes according to the pre-defined ordering. Each sequence has a unique logical index. The ordering of sequences is identified by the logical indexes of the sequences, with each logical index uniquely mapped to a generating index. When a UE needs to transmit, it produces a second sequence using the received indication of the logical index of the first sequence and an auxiliary parameter and then produces a transmission signal by modulating the second sequence.

CLAIM OF PRIORITY UNDER 35 U.S.C. 119(e)

The present application is a Continuation of application Ser. No.12/184,239 filed Jul. 31, 2008, now U.S. Pat. No. 8,773,968, whichclaims priority to and incorporates by reference U.S. provisionalapplication No. 60/954,194 filed on Aug. 6, 2007, entitled “PreambleSequence Planning for LTE Random Access.” The present application alsoclaims priority to and incorporates by reference U.S. provisionalapplication No. 60/970,737 filed on Sep. 7, 2007, entitled “OptimizedSequence Ordering and Signature Mapping for Random Access Preamble inWireless Networks.” The present application also claims priority to andincorporates by reference U.S. provisional application No. 60/972,939filed on Sep. 17, 2007, entitled “Optimized Sequence Ordering andSignature Mapping for Random Access Preamble in Wireless Networks.” Thepresent application also claims priority to and incorporates byreference U.S. provisional application No. 60/975,276 filed on Sep. 26,2007, entitled “Random Access Preamble Sequences Grouping and Ordering.”The present application also claims priority to and incorporates byreference U.S. provisional application No. 60/988,508 filed on Nov. 16,2007, entitled “Random Access Preamble Sequence Ordering in FrequencyDomain.”

FIELD OF THE INVENTION

This invention generally relates to wireless cellular communication, andin particular to a non-synchronous request channel for use in orthogonaland single carrier frequency division multiple access (OFDMA) (SC-FDMA)systems.

BACKGROUND OF THE INVENTION

Wireless cellular communication networks incorporate a number of mobileUEs and a number of NodeBs. A NodeB is generally a fixed station, andmay also be called a base transceiver system (BTS), an access point(AP), a base station (BS), or some other equivalent terminology. Asimprovements of networks are made, the NodeB functionality evolves, so aNodeB is sometimes also referred to as an evolved NodeB (eNB). Ingeneral, NodeB hardware, when deployed, is fixed and stationary, whilethe UE hardware is portable.

In contrast to NodeB, the mobile UE can comprise portable hardware. Userequipment (UE), also commonly referred to as a terminal or a mobilestation, may be fixed or mobile device and may be a wireless device, acellular phone, a personal digital assistant (PDA), a wireless modemcard, and so on. Uplink communication (UL) refers to a communicationfrom the mobile UE to the NodeB, whereas downlink (DL) refers tocommunication from the NodeB to the mobile UE. Each NodeB contains radiofrequency transmitter(s) and the receiver(s) used to communicatedirectly with the mobiles, which move freely around it. Similarly, eachmobile UE contains radio frequency transmitter(s) and the receiver(s)used to communicate directly with the NodeB. In cellular networks, themobiles cannot communicate directly with each other but have tocommunicate with the NodeB.

Long Term Evolution (LTE) wireless networks, also known as EvolvedUniversal Terrestrial Radio Access Network (E-UTRAN), are beingstandardized by the 3GPP working groups (WG). OFDMA and SC-FDMA (singlecarrier FDMA) access schemes were chosen for the down-link (DL) andup-link (UL) of E-UTRAN, respectively. User Equipments (UE's) are timeand frequency multiplexed on a physical uplink shared channel (PUSCH),and a fine time and frequency synchronization between UE's guaranteesoptimal intra-cell orthogonality. In case the UE is not UL synchronized,it uses a non-synchronized Physical Random Access Channel (PRACH), andthe Base Station (also referred to as eNodeB) provides back someallocated UL resource and timing advance information to allow the UEtransmitting on the PUSCH. The 3GPP RAN Working Group 1 (WG1) has agreedon the preamble based physical structure of the PRACH. RAN WG1 alsoagreed on the number of available preambles that can be usedconcurrently to minimize the collision probability between UEs accessingthe PRACH in a contention-based manner. These preambles are multiplexedin CDM (code division multiplexing) and the sequences used are ConstantAmplitude Zero Auto-Correlation (CAZAC) sequences. All preambles aregenerated by cyclic shifts of a number of root sequences, which areconfigurable on a cell-basis.

Depending on whether contention is involved or not, a Random Access (RA)procedure is classified into contention based and non-contention based(or contention-free). While the contention based procedure can be usedby any accessing UE in need of uplink connection, the non-contentionbased is only applicable to handover and downlink data arrival events.In both procedures, a RA preamble is transmitted by the accessing UE toallow NodeB to estimate, and if needed, adjust the UE transmission timeto within a cyclic prefix. It is agreed that there are 64 total RApreambles allocated for each cell of a NodeB, and each NodeB dynamicallyconfigures two disjoint sets of preambles to be used by the two RAprocedures separately. The set for contention-based is broadcasted toall UEs by the NodeB, and the rest of the preambles in the other set areassigned by the NodeB one by one to the UEs in contention-freeprocedure.

Zadoff-Chu (ZC) sequence has been selected as RA preambles for LTEnetworks. Specifically, a cell can use different cyclic shifted versionsof the same ZC root sequence, or other ZC root sequences if needed, asRA preambles. Depending on whether a cell supports high-speed UEs (i.e.,a high-speed cell) or not, sequence and cyclic shift allocation to acell may differ.

The non-synchronized PRACH is multiplexed with scheduled data in aTDM/FDM manner. It is accessible during PRACH slots of duration T_(RA)and period T_(RA). The general operations of the physical random accesschannels are described in the specifications for evolved universalterrestrial radio access (EUTRA), for example: “3^(rd) GenerationPartnership Project; Technical Specification Group Radio Access Network;Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channelsand Modulation (Release 8).”, as defined by the 3GPP working groups(WG). The EUTRA is sometimes also referred to as 3GPP long-termevolution (3GPP LTE).

BRIEF DESCRIPTION OF THE DRAWINGS

Particular embodiments in accordance with the invention will now bedescribed, by way of example only, and with reference to theaccompanying drawings:

FIG. 1 is a pictorial of an illustrative telecommunications network thatsupports transmission of multiplexed random access preambles;

FIG. 2 is an illustrative up-link time/frequency allocation for randomaccess channel use in the network of FIG. 1;

FIG. 3 illustrates a non-synchronized physical random access channel(PRACH) preamble structure in time domain for use in the uplinktransmission of FIG. 2;

FIG. 4 is an illustration of the PRACH preamble structure in frequencydomain for use in the uplink transmission of FIG. 2;

FIG. 5 is a plot illustrating the cubic metric (CM) of the set ofZadoff-Chu (ZC) sequences plotted according to the ZC_normal numericordering of generating index;

FIG. 6 is a plot illustrating the CM of the ZC sequences plottedaccording to CM ordering;

FIG. 7 is a plot illustrating CM of ZC sequences with high-speed cellsize ordering;

FIG. 8A is a plot illustrating the CM at high speed with combined hybridsequence ordering;

FIG. 8B is a plot illustrating the maximum allowed cyclic shift(S_(max)) of the hybrid sequence ordering of the plot of FIG. 8A;

FIG. 9 illustrates mapping of signature opportunity onto physical CS-ZCsequences;

FIG. 10 illustrates mapping of contention-based signature sets used formessage-3 size indication and contention-free signatures in whichcontention-free signatures are mapped last;

FIG. 11 illustrates mapping of contention-based signature sets used formessage-3 size indication and contention-free signatures in whichcontention-free signatures are mapped first;

FIG. 12 illustrates mapping of contention-free and contention-basedsignatures;

FIG. 13 illustrates mapping of contention-based signature sets used formessage-3 size indication and contention-free signatures;

FIG. 14 is a flow diagram illustrating operation of a signaling processfor selecting a preamble configuration for transmission of the preambleof FIG. 3;

FIG. 15 is a block diagram of an illustrative transmitter fortransmitting the preamble structure of FIG. 3;

FIG. 16 is a block diagram Illustrating the network system of FIG. 1;and

FIG. 17 is a block diagram of a cellular phone for use in the network ofFIG. 1.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Disclosed herein are various systems and methods for employing a randomaccess channel in a wireless network to accommodate user equipmentoperating in cells of varying sizes. Embodiments of the disclosedinvention may be used to access a wireless network, such as atelecommunications system, employing random access techniques. A varietyof wireless networks employ random access techniques, for example theEnhanced Universal Terrestrial Radio Access Network (E-UTRAN), currentlybeing standardized by the 3GPP working groups. The disclosed embodimentsof the invention are applicable to all such networks. The disclosedembodiments include apparatus for transmitting random access signals anda method for transmitting a random access signal optimized for cellularcoverage and high-speed UEs.

Embodiments of the present disclosure are directed, in general, towireless communication systems, and can be applied to generate randomaccess transmissions. Random access transmissions may also be referredto as ranging transmissions, or other analogous terms.

User Equipment (“UE”) may be either up-link (“UL”) synchronized or ULnon-synchronized. That is, UE transmit timing may or may not be adjustedto align UE transmissions with NodeB transmission time slots. When theUE UL has not been time synchronized, or has lost time synchronization,the UE can perform a non-synchronized random access to requestallocation of up-link resources. Additionally, a UE can performnon-synchronized random access to register itself at the access point,or for numerous other reasons. Possible uses of random accesstransmission are many, and do not restrict the scope of the presentdisclosure. For example, the non-synchronized random access allows theNodeB to estimate, and if necessary, to adjust the UE's transmissiontiming, as well as to allocate resources for the UE's subsequent up-linktransmission. Resource requests from UL non-synchronized UEs may occurfor a variety of reasons, for example: new network access, data ready totransmit, or handover procedures.

These RA preambles are multiplexed in CDM (code division multiplexing)and the sequences used are Constant Amplitude Zero Auto-Correlation(CAZAC) sequences. All preambles are generated by cyclic shifts of anumber of root sequences, which are configurable on a cell-basis. Inorder to minimize the signaling overhead, only one root sequence isbroadcasted in the cell, and the UE derives the remaining sequencesaccording to a pre-defined order. For LTE networks, a cyclic shiftrestriction rule has been adopted to select usable cyclic shift of agiven sequence for high-speed UEs, which essentially put a constraint onthe sequence allocation for high-speed cells. The problem is that, givena LTE network of mixed cells in terms of cell size and supported UEspeed, what sequence reordering and allocation should be used to providethe most efficient yet cost-effective sequence planning.

FIG. 1 shows an illustrative wireless telecommunications network 100.The illustrative telecommunications network includes base stations 101,102, and 103, though in operation, a telecommunications network mayinclude more base stations or fewer base stations. Each of base stations101, 102, and 103 is operable over corresponding coverage areas 104,105, and 106. Each base station's coverage area is further divided intocells. In the illustrated network, each base station's coverage area isdivided into three cells. Handset or other UE 109 is shown in Cell A108, which is within coverage area 104 of base station 101. Base station101 is transmitting to and receiving transmissions from UE 109. As UE109 moves out of Cell A 108, and into Cell B 107, UE 109 may be “handedover” to base station 102. Assuming that UE 109 is synchronized withbase station 101, UE 109 likely employs non-synchronized random accessto initiate handover to base station 102. The distance over which arandom access signal is recognizable by base station 101 is a factor indetermining cell size.

When UE 109 is not up-link synchronized with base station 101,non-synchronized UE 109 employs non-synchronous random access (NSRA) torequest allocation of up-link 111 time or frequency or code resources.If UE 109 has data ready for transmission, for example, traffic data,measurements report, tracking area update, etc., UE 109 can transmit arandom access signal on up-link 111 to base station 101. The randomaccess signal notifies base station 101 that UE 109 requires up-linkresources to transmit the UE's data. Base station 101 responds bytransmitting to UE 109, via down-link 110, a message containing theparameters of the resources allocated for UE 109 up-link transmissionalong with a possible timing error correction. After receiving theresource allocation and a possible timing adjustment message transmittedon down-link 110 by base station 101, UE 109 may adjust its transmittiming, to bring the UE 109 into synchronization with base station 101,and transmit the data on up-link 111 employing the allotted resourcesduring the prescribed time interval.

UE 109 is traveling in a direction with a ground speed as indicated by112. The direction and ground speed results in a speed component that isrelative to serving NodeB 101. Due to this relative speed of UE movingtoward or away from its serving NodeB a Doppler shift occurs in thesignals being transmitted from the UE to the NodeB resulting in afrequency shift and/or frequency spread that is speed dependent.

FIG. 2 illustrates an exemplary up-link transmission frame 202, and theallocation of the frame to scheduled and random access channels. Theillustrative up-link transmission frame 202, comprises a plurality oftransmission sub-frames. Sub-frames 203 are reserved for scheduled UEup-link transmissions. Interspersed among scheduled sub-frames 203, aretime and frequency resources allocated to random access channels 201,210. In the illustration of FIG. 2, a single sub-frame supports tworandom access channels. Note that the illustrated number and spacing ofrandom access channels is purely a matter of convenience; a particulartransmission frame implementation may allocate more or less resource torandom access channels. Including multiple random access channels allowsmore UEs to simultaneously transmit a random access signal withoutcollision. However, because each UE Independently chooses the randomaccess channel on which it transmits, collisions between UE randomaccess signals may occur.

FIG. 3 illustrates an embodiment of a random access signal 300. Theillustrated embodiment comprises cyclic prefix 302, random accesspreamble 304, and guard interval 306. Random access signal 300 is onetransmission time interval 308 in duration. Transmission time interval308 may comprise one or more sub-frame 203 durations. Note that the timeallowed for random access signal transmission may vary, and thisvariable transmission time may be referred to as transmitting over avarying number of transmission time intervals, or as transmitting duringa transmission time interval that varies in duration. This disclosureapplies the term “transmission time interval” to refer to the timeallocated for random access signal transmission of any selectedduration, and it is understood that this use of the term is equivalentto uses referring to transmission over multiple transmission timeintervals. The time period allotted for random access signaltransmission may also be referred to as a random access time slot.

Cyclic prefix 302 and guard interval 306 are typically of unequalduration. Guard interval 306 has duration equal to approximately themaximum round trip delay of the cell while cyclic prefix 302 hasduration equal to approximately the sum of the maximum round trip delayof the cell and the maximum delay spread. As indicated, cyclic prefixand guard interval durations may vary from the ideal values of maximumround trip delay and maximum delay spread while effectively optimizingthe random access signal to maximize coverage. All such equivalents areintended to be within the scope of the present disclosure.

Round trip delay is a function of cell size, where cell size is definedas the maximum distance d at which a UE can interact with the cell'sbase station. Round trip delay can be approximated using the formulat=d*20/3 where t and d are expressed in microseconds and kilometersrespectively. The round-trip delay is the two-way radio propagationdelay in free space, which can be approximated by the delay of theearlier radio path. A typical earlier path is the line-of-sight path,defined as the direct (straight-line) radio path between the UE and thebase station. When the UE is surrounded by reflectors, its radiatedemission is reflected by these obstacles, creating multiple, longertraveling radio paths. Consequently, multiple time-delayed copies of theUE transmission arrive at the base station. The time period over whichthese copies are delayed is referred to as “delay spread,” and forexample, in some cases, 5 μs may be considered a conservative valuethereof.

Cyclic prefix 302 serves to absorb multi-path signal energy resultingfrom reflections of a signal transmitted in the prior sub-frame, and tosimplify and optimize equalization at the NodeB 101 receiver by reducingthe effect of the channel transfer function from a linear (or aperiodic)correlation to a cyclic (or periodic) correlation operated across theobservation interval 310. Guard Interval 306 follows random accesspreamble 304 to prevent interference between random access preamblesignal 304 and any transmission in the subsequent sub-frame on the sametransmission frequencies used by random access preamble signal 304.

Random access preamble signal 304 is designed to maximize theprobability of preamble detection by the NodeB and to minimize theprobability of false preamble detections by the NodeB, while maximizingthe total number of resource opportunities. Embodiments of the presentdisclosure utilize constant amplitude zero autocorrelation (“CAZAC”)sequences to generate the random access preamble signal. CAZAC sequencesare complex-valued sequences with the following two properties: 1)constant amplitude (CA), and 2) zero cyclic autocorrelation (ZAC).

FIG. 4 is a more detailed illustration of the PRACH preamble structurefor use in the uplink transmission of FIG. 2. FIG. 4 illustrates thepreamble structure in frequency domain, while FIG. 3 illustrated thepreamble structure in time domain. Physical uplink shared channel(PUSCH) structure 402 illustrates the seventy-two sub-carriers 404 thatare each 15 kHz when the frequency resources are allocated to PUSCH,while physical random access channel (PRACH) preamble structure 406illustrates the 864 sub-carriers 408 that are each 1.25 kHz when thefrequency resources are allocated to PRACH. This embodiment uses guardbands 412, 414 to avoid the data interference at preamble edges.

The preamble sequence is a long CAZAC complex sequence allocated to theUE among a set of R_(S) possible sequences. These sequences are builtfrom cyclic shifts of a CAZAC root sequence. If additional sequences areneeded, they are built from cyclic shifts of other CAZAC root sequences.

Well known examples of CAZAC sequences include, but are not limited to:Chu Sequences, Frank-Zadoff Sequences, Zadoff-Chu (ZC) Sequences, andGeneralized Chirp-Like (GCL) Sequences. A known set of sequences withCAZAC property is the Zadoff-Chu N-length sequences defined as follows

$a_{k} = {\exp\;\left\lbrack {{- {j2\pi}}\;\frac{M}{N}\left( {\frac{k\left( {k + 1} \right)}{2} + {qk}} \right)} \right\rbrack}$where M is relatively prime to N, N odd, and q any integer. The M is thegenerating index of ZC sequence, which can also be referred to asphysical root sequence index, physical root sequence number, and others,in various embodiments. Each root ZC sequence has a unique generatingindex.

The latter constraint on N also guarantees the lowest andconstant-magnitude cross-correlation √{square root over (N)} betweenN-length sequences with different values of M: M₁, M₂ such that (M₁−M₂)is relatively prime to N. As a result, choosing N a prime number alwaysguarantees this property for all values of M<N, and therefore maximizesthe set of additional sequences, non orthogonal, but with optimalcross-correlation property. On top of providing additional sequences fora UE to chose among in a given cell, these sequences are also intendedto be used in neighboring cells, so as to provide good inter-cellInterference mitigation. In this disclosure, the terms: Zadoff-Chu, ZC,and ZC CAZAC, are used interchangeably. The term CAZAC denotes any CAZACsequence, ZC or otherwise.

In various embodiments of the present disclosure, random access preamblesignal 304 comprises a CAZAC sequence, such as a ZC sequence. Additionalmodifications to the selected CAZAC sequence can be performed using anyof the following operations: multiplication by a complex constant, DFT,IDFT, FFT, IFFT, cyclic shifting, zero-padding, sequenceblock-repetition, sequence truncation, sequence cyclic-extension, andothers. Thus, in one embodiment of the present disclosure, a UEconstructs random access preamble signal 304 by selecting a CAZACsequence, possibly applying a combination of the described modificationsto the selected CAZAC sequence, modulating the modified sequence, andtransmitting the resulting random access signal over the air.

Further aspects of embodiments of the Random Access (RA) channeloperation are described in related U.S. Pat. No. 8,098,745 filed 27 Mar.2007, entitled “Random Access Structure For Wireless Networks” by PierreBertrand, Jing Jiang, Tarik Muharemovic and Shantanu Kangude which isincorporated herein by reference; and in related U.S. patent applicationSer. No. 11/833,329, filed 3 Aug. 2007, now U.S. Pat. No. 8,259,598,entitled “Random Access Structure For Optimal Cell Coverage” by PierreBertrand, Anand Dabak and Jing Jiang which is incorporated by referenceherein.

The time-continuous PRACH preamble signal s(t) is defined by:

${s(t)} = {\beta_{PRACH}{\sum\limits_{k = 0}^{N_{ZC} - 1}\;{\sum\limits_{n = 0}^{N_{ZC} - 1}\;{{x_{u,v}(n)} \cdot {\mathbb{e}}^{{- j}\;\frac{2\pi\;{nk}}{N_{ZC}}} \cdot {\mathbb{e}}^{j\; 2{\pi{({k + \varphi + {K{({k_{0} + {1\text{/}2}})}}})}}\Delta\;{f_{RA}{({t - T_{CP}})}}}}}}}$     where      0 ≤ t < T_(SEQ) + T_(CP),β_(PRACH) is an amplitude scaling factor andk ₀ =n _(PRB) ^(RA) N _(sc) ^(RB) −N _(RB) ^(UL) N _(sc) ^(RB)/2.

T_(SEQ) is the sequence duration and T_(CP) is the cyclic prefixduration. N_(sc) ^(RB) is the number of data subcarriers per resourceblock (RB) and N_(RB) ^(UL) is the total number of resource blocksavailable for UL transmission. The location in the frequency domain iscontrolled by the parameter n_(PRB) ^(RA), expressed as a resource blocknumber configured by higher layers and fulfilling0≦n _(PRB) ^(RA) ≦N _(RB) ^(UL)−6The factorK=Δf/Δf _(RA)accounts for the difference in subcarrier spacing between the randomaccess preamble and uplink data transmission. The variable φ defines afixed offset determining the frequency-domain location of the randomaccess preamble within the resource blocks. The PRACH signal takes thefollowing value for φ: φ=7.

The above numerical example applies to preamble burst formats 0 to 3.Same design principle is also applicable to burst format 4 withdifferent numerical values.

The E-UTRA PRACH preamble is a Cyclically Shifted Zadoff-Chu (CS-ZC)sequence, as described in 3GPP TS 36.211 v1.0.0 (2007-03), TechnicalSpecification Group Radio Access Network; Physical Channels andModulation (Release 8). The construction of these sequences uses theConstant Amplitude Zero Auto-Correlation (CAZAC) property of theZadoff-Chu (ZC) sequences by cyclically shifting a ZC root sequence byan amount guaranteed to maintain the orthogonality of the resultantsequences. For example, a ZC root sequence may be shifted by an integermultiple of the cell's maximum round trip delay plus the delay spread,to generate a set of orthogonal sequences. Additional preamble sequencesmay be generated by cyclically shifting other ZC root sequences. As aresult, the cyclic shift and corresponding number of root sequences usedin a cell are a function of the cell size. Generally, only one ZC rootsequence index is signaled (implicitly or explicitly) to the UE,regardless the actual number of root sequences required in a cell. TheUE can derive the subsequent root sequence indexes according to apre-defined ordering. Before looking at the possible choices for this ZCordering, we first list the various aspects that influence this design.

In this disclosure, the cyclically shifted or phase ramped CAZAC-likesequence is sometimes denoted as cyclic shifted base sequence, cyclicshifted root sequence, phase ramped base sequence, phase ramped rootsequence, or any other equivalent term. In other places, the CAZAC-likesequence is generally referred to as the second sequence.

Cyclic Shift Configurations

In the present embodiment, a sequence length of 839 is assumed whichmeans that ten bits are required to signal one Zadoff-Chu generatingindex. Given that up to 64 sequences may need to be signaled, it ishighly desirable to minimize the associated overhead due to signalingmultiple sequences. This is achieved by signaling only one logical indexand the UE derives the subsequent indexes according to a pre-definedordering. Each ZC sequence has a unique logical index. The ordering ofsequences is identified by the logical indexes of the sequences, witheach logical index uniquely mapped to a generating index. Note that inone embodiment, the ordering of sequences is the same as the ordering oftheir generating indexes. From the above considerations, cyclic shiftand ZC generating indexes are configured on a cell basis. The cyclicshift value (or increment) is taken from among sixteen pre-definedvalues.

Random Access Preamble Signaling

As described above, the minimum Random Access preamble parameters thatneed be signaled are 19 bits:

Cyclic shift configuration (4 bits)

Unrestricted cyclic shift set or restricted cyclic shift set (1 bit)

1^(st) ZC logical index (10 bits)

PRACH timing configuration (4 bits)

The signaling of cyclic shift configuration the cyclic shift set type(unrestricted or restricted) is to determine the value of cyclic shiftto use. In various embodiments of signaling method, either one or twoauxiliary parameters can be used to signal a cyclic shift value to use.

One auxiliary parameter is a 1-bit flag that signals whether the currentcell is a high speed cell or not. For high speed cells, cyclic shiftrestrictions apply and the UE identifies which cyclic shifts must not beused. The excellent auto/cross-correlation of CS-ZC sequences allowssupporting a much larger number of signature opportunities, 64, than the16 Walsh-Hadamard opportunities offered in the current UMTS RACHpreamble, and this with very little performance loss. However, the aboveperformance assumes no or little Doppler spread or frequency shift, inpresence of which, the CS-ZC sequence loses its zero-auto-correlationproperty. Indeed, high Doppler shifts induce correlation peaks in thereceiver's bank of correlators offset by d_(u) from the desired peakwhen the u-th root sequence of length N_(zc) is transmitted. The cyclicoffset d_(u) depends on the generating index u, which can be derivedfrom (1), or a mathematically equivalent expression, as

$\begin{matrix}{d_{u} = \left\{ \begin{matrix}{u^{- 1}{mod}\; N_{ZC}} & {0 \leq {u^{- 1}{mod}\mspace{11mu} N_{ZC}} < {N_{ZC}\text{/}2}} \\{N_{ZC} - {u^{- 1}{mod}\; N_{ZC}}} & {otherwise}\end{matrix} \right.} & (1)\end{matrix}$Where u⁻¹ mod N_(ZC) is the modulo inverse of d_(u), in the sense ofd _(u) ·u=1 mod N _(ZC)  (2)

A solution to this problem of loss of zero-auto-correlation property is“masking” cyclic shift positions where side peaks are expected in the ZCroot sequence. Therefore, for high speed cells where cyclic shiftrestrictions apply, more ZC root sequences will need to be configuredcompared to low-medium speed cells. Another impact of the side peaks isthat they restrict the possible cyclic shift range so as to prevent fromside peaks to occur within the used cyclic shift region.

It results that, in the case where the ZC sequences are not ordered byincreasing maximum supportable high-speed cell size, there will be caseswhere, in a high-speed cell, some of the ZC sequences following the1^(st) sequence signaled by the NodeB are not compliant with the cellradius of that cell. In which cases, these sequences are skipped.

To reduce NodeB signaling, in one embodiment, a single logical index isbroadcasted to all UEs in a cell as the starting root sequence allocatedto this cell for contention-based random access. In addition to that,the number of signatures for contention-based RA is also given, so thatwith d_(u)-based ordering, an accessing UE can derive from the orderingtable the available root sequences, hence the usable signatures, giventhe usable cyclic shifts for each root sequence. Since a subset ofsignatures may be reserved for contention-free RA, in one embodimentNodeB can reserve the signatures with the lowest cubic metrics forcontention-free RA, so that a UE uses the remaining subset of signaturesof high cubic metrics for contention-based RA.

Cubic Metric of Zadoff-Chu Sequences

FIG. 5 is a plot illustrating the cubic metric (CM) of the set of 838Zadoff-Chu (ZC) sequences plotted according to normal numeric orderingof their generating indexes. The cubic metric (CM) of the 838 possibleZC sequences is an important parameter to consider when allocatingdifferent ZC sequences to a cell. Indeed, as shown in FIG. 5, the CM canvary by up to 2.5 dB depending on the ZC sequences used in a cell, whichresult in unfair detection probability depending on the signaturerandomly selected by the UE and reduce the overall coverage performanceof the PRACH.

The CM value for a given sequence is calculated as follows:

${CM} = {\frac{{20\mspace{11mu}\log_{10}\left\{ {{rms}\;\left\lbrack {v_{norm}^{3}(t)} \right\rbrack} \right\}} - 1.52}{1.56}{dB}}$for the amount by which the power capability of a UE power amplifiermust be de-rated for LTE signals with 3.84 MHz nominal bandwidth. Otherembodiments may use variations of this calculation to determine a CMvalue.Contention-free Access

The unpredictable latency of the Random Access procedure may becircumvented for some use-cases where low-latency is required, such asinter-eNodeB handover and DL traffic resume of a DRX UE in active mode,by allocating dedicated signatures to the UE on a need basis

Preamble Information

In the present embodiment, the signature sent by the UE out of the 64available PRACH signatures per cell carries a five bit random ID, andone bit to indicate information on size of message-3 (of the RandomAccess procedure as defined in the 3GPP TS 36.300 v8.1.0 (2007-06),Technical Specification Group Radio Access Network; Evolved UniversalTerrestrial Radio Access (E-UTRA) and Evolved Universal TerrestrialRadio Access Network (E-UTRAN); Overall description; Stage 2; (Release8)) or requested resource blocks (FFS) limited by radio conditions. Thegroups of signatures that are used for indicating the one bitinformation, as well as necessary thresholds are broadcast by the eachNodeB for the served cell. In other words, two possible message sizesare broadcasted in the cell and the UE chooses the message sizedepending on its radio conditions (the worse the radio condition, thesmaller the message size) and the PRACH use case (some use cases requireonly few bits to transmit so that choosing the small message size savesunnecessary allocated resources). It should be understood that in otherembodiments, different numbers of signatures and ID sizes may be used.

Sequence Ordering

Several schemes for performing sequence ordering will be describedherein. Different embodiments of the present invention may use one or acombination of these schemes:

-   1. CM-based sequence ordering-   2. High-speed cell-size (or S_(max)-based) ordering;-   3. Hybrid orderings:    -   3a. CM-based sequence grouping with alternate S_(max) ordering        in consecutive groups    -   3b. S_(max)-based sequence grouping with alternate CM ordering        in consecutive groups    -   3c. Combination of 3a and 3b;-   4. Hybrid orderings in both time and frequency domain, without using    a transmit filter.    CM-Based Ordering

Since the CM is a measure of the required power back-off at the UE, thisvalue can be optimized depending e.g. on the cell size. For example, lowCM ZCs can be allocated to larger cells (where cell-edge UEs will mostlikely have tougher propagation conditions). FIG. 5 shows the CMvariation as a function of the ZC generating index. As can be seen, ifN_(ZC) is the ZC sequence length, the CM roughly follows an increasingtrend as generating index increases in addition to the symmetry betweenthe r-th and (N−r)-th sequences. As a result, the simplest ZC sequencegenerating index ordering is: 1, N−1, 2, N−2, . . . , r, N−r, . . . ,└N/2┘, ┐N/2┌. A more exact ordering by increasing CM can be obtainedfrom FIG. 6

This ordering guarantees that when multiple ZC sequences are to be usedin the same cell, they have similar CM properties, which aims atproviding homogeneous detection probability of all root sequences usedin a cell. It also allows for a CM-based ZC sequence planning. Forexample, low CM ZCs can be allocated to larger cells (where cell-edgeUEs will most likely have tougher propagation conditions).

High-speed Cell-size Ordering

In another embodiment, sequences may be ordered based on maximumsupportable high-speed cell size. This assumes that a sequencerestriction rule is applied for high-speed cells, that is, twoconditions are to be satisfied by the ZC root sequences allocated to ahigh-speed cell. The two conditions are, respectively,d_(u)≧N_(CS)  Condition #1:andd _(u)≦(N _(ZC) −N _(CS))/2  Condition #2:The parameters N_(ZC) and N_(CS) are the length of ZC sequence and thevalue of allowed cyclic shift at high speed, respectively, and d_(u) isas defined before.

The maximum supportable cell radius of a ZC sequence at high speed isdefined asR _(max)=(S _(max) ·T _(p)−τ_(max))×3/20  (3)

in kilometer, with T_(p) being the preamble sample period inmicro-second, τ_(max) being the maximum delay spread of the cell inmicro-second, and S_(max) being the maximum allowed cyclic shift of a ZCsequence at high speed computed fromS _(max)=min(d _(u) ,N _(ZC) −d _(u) ,|N _(ZC)−2d _(u)|).  (4)

Since S_(max) is linearly proportional to the maximum supportable cellsize, with S_(max)-based reordering, sequence allocation can be startedfrom the largest high-speed cell in an increasing order of logicalindex. That is, once a logical index with its R_(max) above cell radiusis identified as the starting logical index for this cell, the followingsuccessive subset is then allocated together for the total requiredsignatures by counting the usable cyclic shifts for each root sequencebased on conditions 1 and 2. The allocation then proceeds to the nextlargest high-speed cell. If it is out of consecutive sequences for ahigh-speed cell, the allocated sequences to the next largest high-speedcell can be shifted to the high S_(max) end to leave just enough spacefor the cell to fit in if there is still space to its high end. Theshift should start from low end to high end corresponding to theallocation to the next largest cell one by one. Low-speed cells areallocated after high-speed cells and they use consecutive subsets at thelow end among remaining sequences. Allocation starts from the low endfor low-speed cells. If it is out of consecutive sequences for alow-speed cell, the allocated sequences can be shifted toward high endone by one. This way, the most efficient use of all root sequences byboth high-speed and low-speed cells is achieved.

It should be noted that due to the symmetry between the u-th rootsequence and the (K−u)-th root sequence in both CM and S_(max), onlyhalf of this Table needs to be stored at each UE given a pre-assumedordering of u and (K−u). The same concept applies when ZC sequences areused in frequency-domain, where a different but similar table can beused.

Hybrid Approach

When both performance metrics, CM and S_(max), are of concern insequence ordering, a hybrid approach can be used to accommodate theconflicting ordering based on both. In particular, two levels ofsequence grouping are used with the first level of grouping based on onemetric, and the second level of grouping based on the other metric. Thesecond-level grouping can be viewed as a sub-grouping within onefirst-level group. The metric of a hybrid approach is the efficientsequence allocation to both low-speed and high-speed cell, while thegood cell coverage and persistent preamble detection performance can beachieved at the same time.

For a hybrid sequence ordering, a set of CM values and a set ofhigh-speed cyclic shift values are predefined for two levels of sequencegrouping.

S_(max)-based Sequence Grouping with Alternate CM Ordering inConsecutive Groups

In this method, the ZC root sequences are grouped according to theirmaximum supportable cell radius (or maximum allowed cyclic shift S_(max)at high speed), and sequences in each group are ordered according totheir cubic metric (CM) respectively. The intra-group sequence orderingin CM takes alternate increasing and decreasing directions acrossconsecutive groups. This ordering arrangement ensures that consecutivesequences have close CM values when allocated to a cell, such thatconsistent cell coverage and preamble detection can be achieved in onecell. Sequences also suffer less discontinuity in the CM when notallocated.

Specifically, ZC root sequences are first grouped according to theirrespective maximum supportable cell radius to facilitate sequenceplanning including high-speed cells, where a sequence group g is the setof all root sequences with their maximum allowed cyclic shifts (S_(max))lying between two consecutive high-speed N_(CS) values according toN _(CS)(g)≦S _(max) <N _(CS)(g+1), for g=1, . . . ,G+1,with N_(CS)(1)=1 and N_(CS)(G+2)=N_(ZC) as boundary values, and Ghigh-speed cyclic shift values N_(CS)(g) for g=2, . . . , G+1.CM-based Sequence Grouping with Alternate S_(max) Ordering inConsecutive Groups

This method groups the sequences according to their CM values first,then within each group, the sequences are ordered according to theirmaximum allowed cyclic shifts S_(max) at high speed. Alternate S_(max)ordering is used in adjacent groups. An example design with CM groupingvalues is based on 1.2 dB, 1.7 dB, 2.2 dB, that is 4 CM-based sequencegroups are used, with their group CM (in dB) in the intervals of (−∞,1.2], (1.2, 1.7], (1.7, 2.2], (2.2, ∞).

Combined Hybrid Ordering

This embodiment provides a sequence ordering which combines the abovetwo alternatives of hybrid approach. The sequences are first divide intotwo CM groups with a fixed CM threshold, say 1.2 dB, then within each CMgroup, the sequences are furthered grouped according to their maximumallowed cyclic shifts values S_(max) at high speed. Alternate S_(max)ordering is used in two CM groups for smooth S_(max) transition at CMgroup boundaries. Within each S_(max) group, the sequences are orderedaccording to their CM values, with alternate CM ordering in adjacentS_(max) groups to ensure smooth CM transition at both S_(max) group andCM group boundaries. To facilitate smooth CM transition at both S_(max)group and CM group boundaries, an even number of S_(max) groups is used.Note that sequence order is interpreted cyclic so that the firstsequence is consecutive to the last sequence in the ordered sequenceset.

FIG. 8A shows an example of combined hybrid sequence ordering with a ZCsequences of length 839 and a set of 15 high-speed cyclic shift valuesof {15, 18, 22, 26, 32, 38, 46, 55, 68, 82, 100, 128, 158, 202, 237}.Together with the boundary values, the entire set of 33 N_(CS)(g) values{1, 15, 18, 22, 26, 32, 38, 46, 55, 68, 82, 100, 128, 158, 202, 237,839, 2237, 202, 158, 128, 100, 82, 68, 55, 46, 38, 32, 26, 22, 18, 15,1} divide the sequences into 32 groups, with the g-th group satisfyingN _(CS)(g)≦S _(max) <N _(CS)(g+1), for g=1, . . . ,G+1,andN _(CS)(g+1)≦S _(max) <N _(CS)(g), for g=G+2, . . . ,2G+2,for G=15 and 2(G+1) groups. The set of 15 high-speed cyclic shift valuesare pre-defined for S_(max)-based sequence grouping. A single CMthreshold is set to 1.2 dB in this example, such that in the low CMgroup 802 the sequence are further S_(max)-grouped according toincreasing N_(CS)(g) values for g=1, . . . , 17, and that in the high CMgroup 804, the sequences are further S_(max)-grouped according todecreasing N_(CS)(g) values for g=17, . . . , 33, as illustrated in FIG.8B. Note that in the above set of N_(CS)(g) values,N_(CS)(g)=N_(CS)(2G+4−g) for alternate S_(max) grouping order in two CMgroups.

For example, groups 806 formed by 1≦S_(max)<15 are denoted in FIG. 8B.

Note that with any sequence ordering described above, the group ofsequences for planning can be either the entire ordered sequence groupor a subset of it in one embodiment.

CM-based Signature Mapping

As shown in FIG. 7, the CM resulting from consecutive ZC sequences withhigh-speed cell size ordering is almost random within −1 to 2.5 dB. As aresult, consecutive root sequences allocated to a given cell may undergoabrupt CM variations. As a result, in order to limit this drawback, thefollowing rules are followed for the set of ordered sequences:

1. Contention-free signatures are mapped onto the root sequences withlowest CM

2. Signatures indicating the small message-3 size are mapped onto theroot sequences with intermediate CM

3. Signatures indicating the large message-3 size are mapped onto theroot sequences with the largest CM

Rule 1 guarantees more robustness to contention-free signatures, whichare expected to be used by the most critical random access use cases:handover and fast recovering from DRX in case of new DL data. Rules 2and 3 address the fact that a UE that requests a small message-3allocation is likely in poorer radio conditions than a UE requesting alarge message-3 size, and therefore a lower CM will help the former inhaving a successful PRACH transmission.

Hybrid Sequence Ordering with CM-based Signature Mapping

In this embodiment, the above combined hybrid sequence ordering isfurther improved in light of the signature mapping issue discussedabove. By doing so, the robustness of “prioritization” of signaturesdepending on their use cases is added on top of the benefit of thehybrid approach.

Signature Mapping of a Constant Number (64) of Signatures

FIG. 9 illustrates a scheme for mapping sixty-four signatures.Sixty-four signatures are mapped onto sixty-four cyclic shifts availablefrom N root sequences. It is assumed the signature opportunity indexesare mapped onto the cyclic shifted ZC sequences in low speed cells asfollows: signature #1 940 is mapped onto the first ZC sequence 930 inthe list; signature sequence #2 942 is mapped onto the same ZC sequence,right-cyclic-shifted by the cyclic shift value 944 (or increment);subsequent signatures #3 to n are similarly incrementally mapped ontosubsequent right-cyclic-shifted versions of the same ZC sequence untilall possible n cyclic shifts have been obtained. Then, signature #n+1 ismapped onto the next ZC sequence 931 in the list, and the followingsignatures are mapped onto its subsequent right-cyclic-shifted versions.This signature mapping is repeated over all ZC root sequences 932 andstops at sequence #64 946 when 64 sequences were generated. In case ofhigh speed cells, cyclic shift restrictions apply (as described withrespect to Conditions #1 and #2 above) so that some cyclic shiftsskipped.

Mapping of contention-free signatures will now be discussed, as well asthe two contention-based signature sets indicating the size of message-3of the Random Access procedure. When there always are a constant numberof signatures mapped onto the cyclic shifts of the root sequences, thethree above signature sets have to share this total number ofsignatures. The three sets are allocated so as to prioritize thesignature robustness depending on their use case, as discussed above:

-   -   Contention-free signatures are mapped onto the root sequences        with lowest CM    -   Signatures indicating the small message 3 size are mapped onto        the root sequences with intermediate CM    -   Signatures indicating the large message 3 size are mapped onto        the root sequences with the largest CM

As shown in FIGS. 10 and 11 where all available cyclic shifts acrossroot sequences are projected on a single axis for simplicity, this leadsto two possible mappings for contention-based signatures andcontention-free signatures, as follows.

In one scheme, contention-based signatures, starting with the signatureset 1002 indicating the large message-3 size are allocated first, thencontention-based signature set 1004 indicating the small message-3 size,and finally contention-free signatures 1006, as illustrated in FIG. 10.In this case, the ZC sequences within an S_(max) group must be orderedby decreasing CM.

In another scheme, contention-free signatures 1102 are allocated first,then contention-based signatures, starting with the signature set 1104indicating the small message 3 size, and finally contention-basedsignature set 1106 indicating the large message 3 size, as illustratedin FIG. 11. In this case, the ZC sequences within an S_(max) group mustbe ordered by increasing CM.

Signature Mapping of a Non-constant Number Signatures

As illustrated in FIG. 12, when there is an uneven number of cyclicshifts per root sequence to get the 64 signatures, some remaining cyclicshifts 1202 are available at the end of the last root sequence. Thesecan be used for contention-free signatures, so that contention-freesignatures puncture less contention-based signature space. Therefore, ifsignatures need to be reserved for contention-free access, a simplesolution to take advantage of these available cyclic shifts is toallocate these signatures backward starting from the last availablecyclic shift of the last root sequence, as indicated at 1204. Then, themapping of contention-based signature sets indicating the size ofmessage-3 of the Random Access procedure, is done as described above fora constant number of signatures. As Illustrated in FIG. 13 for oneembodiment, the signature set 1302 indicating a large message-3 size ismapped onto the indexes of the contention-based signatures with higherCM values, and the signature set 1304 indicating a small message-3 sizeis mapped onto the remaining contention-based signatures with lower CMvalues.

Hybrid Sequence Ordering in Time and Frequency Domain

In E-UTRA networks, high-speed random access is supported with anadditional set of cyclic shift values for cells of size up to 30 km inradius. This embodiment provides the corresponding sequence ordering infrequency domain based on the time-domain Zadoff-Chu (ZC) sequenceordering by assuming ZC sequences are applied in frequency domaindirectly. The sequence ordering in time domain is derived without usingany transmit filter, along with its dual ordering in frequency domain.The dual ZC sequence index mapping is based on the principle that a ZCsequence with generating index u in time domain corresponds to a rotatedand scaled ZC sequence in frequency domain with a generating index ν of:(u·v=−1)mod N _(ZC), or equivalently,(u·v=N _(ZC)−1)mod N _(ZC),where (·) mod N_(ZC) denotes modulo N_(ZC) operation and N_(ZC) is theZC sequence length of a prime number.

Table 1 lists the time-domain ZC sequence hybrid ordering when assumingno transmit filter. Table 2 lists the frequency-domain ZC sequencehybrid ordering corresponding to the ordering in Table 1.

TABLE 1 Mapping from logical index to generating index for time-domainZC sequences. CM S_(max) N_(CS) Logical grp grp (HS) index Generatingindex Low 1 —  0~23 129 710 140 699 120 719 210 629 168 671 84 755 105734 93 746 70 769 60 779 2 837 1 838 2 15 24~29 56 783 112 727 148 691 318 30~35 80 759 42 797 40 799 4 22 36~41 35 804 73 766 146 693 5 2642~51 31 808 28 811 30 809 27 812 29 810 6 32 52~63 24 815 48 791 68 77174 765 178 661 136 703 7 38 64~75 86 753 78 761 43 796 39 800 20 819 21818 8 46 76~89 95 744 202 637 190 649 181 658 137 702 125 714 151 688 955  90~115 217 622 128 711 142 697 122 717 203 636 118 721 110 729 89750 103 736 61 778 55 784 15 824 14 825 10 68 116~135 12 827 23 816 34805 37 802 46 793 207 632 179 660 145 694 130 709 223 616 11 82 136~167228 611 227 612 132 707 133 706 143 696 135 704 161 678 201 638 173 666106 733 83 756 91 748 66 773 53 786 10 829 9 830 12 100 168~203 7 832 8831 16 823 47 792 64 775 57 782 104 735 101 738 108 731 208 631 184 655197 642 191 648 121 718 141 698 149 690 216 623 218 621 13 128 204~263152 687 144 695 134 705 138 701 199 640 162 677 176 663 119 720 158 681164 675 174 665 171 668 170 669 87 752 169 670 88 751 107 732 81 758 82757 100 739 98 741 71 768 59 780 65 774 50 789 49 790 26 813 17 822 13826 6 833 14 158 264~327 5 834 33 806 51 788 75 764 99 740 96 743 97 742166 673 172 667 175 664 187 652 163 676 185 654 200 639 114 725 189 650115 724 194 645 195 644 192 647 182 657 157 682 156 683 211 628 154 685123 716 139 700 212 627 153 686 213 626 215 624 150 689 15 202 328~383225 614 224 615 221 618 220 619 127 712 147 692 124 715 193 646 205 634206 633 116 723 160 679 186 653 167 672 79 760 85 754 77 762 92 747 58781 62 777 69 770 54 785 36 803 32 807 25 814 18 821 11 828 4 835 16 237384~455 3 836 19 820 22 817 41 798 38 801 44 795 52 787 45 794 63 776 67772 72 767 76 763 94 745 102 737 90 749 109 730 165 674 111 728 209 630204 635 117 722 188 651 159 680 198 641 113 726 183 656 180 659 177 662196 643 155 684 214 625 126 713 131 708 219 620 222 617 226 613 High 17237 456~513 230 609 232 607 262 577 252 587 418 421 416 423 413 426 411428 376 463 395 444 283 556 285 554 379 460 390 449 363 476 384 455 388451 386 453 361 478 387 452 360 479 310 529 354 485 328 511 315 524 337502 349 490 335 504 324 515 18 202 514~561 323 516 320 519 334 505 359480 295 544 385 454 292 547 291 548 381 458 399 440 380 459 397 442 369470 377 462 410 429 407 432 281 558 414 425 247 592 277 562 271 568 272567 264 575 259 580 19 158 562~629 237 602 239 600 244 595 243 596 275564 278 561 250 589 246 593 417 422 248 591 394 445 393 446 370 469 365474 300 539 299 540 364 475 362 477 298 541 312 527 313 526 314 525 353486 352 487 343 496 327 512 350 489 326 513 319 520 332 507 333 506 348491 347 492 322 517 20 128 630~659 330 509 338 501 341 498 340 499 342497 301 538 366 473 401 438 371 468 408 431 375 464 249 590 269 570 238601 234 605 21 100 660~707 257 582 273 566 255 584 254 585 245 594 251588 412 427 372 467 282 557 403 436 396 443 392 447 391 448 382 457 389450 294 545 297 542 311 528 344 495 345 494 318 521 331 508 325 514 321518 22 82 708~729 346 493 339 500 351 488 306 533 289 550 400 439 378461 374 465 415 424 270 569 241 598 23 68 730~751 231 608 260 579 268571 276 563 409 430 398 441 290 549 304 535 308 531 358 481 316 523 2455 752~765 293 546 288 551 284 555 368 471 253 586 256 583 263 576 25 46766~777 242 597 274 565 402 437 383 456 357 482 329 510 26 38 778~789317 522 307 532 286 553 287 552 266 573 261 578 27 32 790~795 236 603303 536 356 483 28 26 796~803 355 484 405 434 404 435 406 433 29 22804~809 235 604 267 572 302 537 30 18 810~815 309 530 265 574 233 606 3115 816~819 367 472 296 543 32 — 820~837 336 503 305 534 373 466 280 559279 560 419 420 240 599 258 581 229 610

TABLE 2 Mapping from logical index to generating index forfrequency-domain ZC sequences. CM S_(max) N_(CS) Logical grp grp (HS)index Generating index Low 1 —  0~23 13 826 6 833 7 832 4 835 5 834 10829 8 831 415 424 12 827 14 825 419 420 1 838 2 15 24~29 15 824 412 42717 822 3 18 30~35 409 430 20 819 21 818 4 22 36~41 24 815 23 816 408 4315 26 42~51 406 433 30 809 28 811 404 435 405 434 6 32 52~63 35 804 402437 37 802 34 805 33 806 401 438 7 38 64~75 400 439 398 441 39 800 43796 42 797 40 799 8 46 76~89 53 786 54 785 393 446 394 445 49 790 396443 50 789 9 55  90~115 58 781 59 780 65 774 392 447 62 777 64 775 389450 66 773 391 448 55 784 61 778 56 783 60 779 10 68 116~135 70 769 73766 74 765 68 771 383 456 381 458 75 764 81 758 71 768 380 459 11 82136~167 92 747 377 462 375 464 82 757 88 751 87 752 370 469 96 743 97742 372 467 374 465 378 461 89 750 95 744 84 755 373 466 12 100 168~203120 719 105 734 367 472 357 482 118 721 368 471 121 718 108 731 101 738359 480 114 725 362 477 123 716 104 735 119 720 366 473 369 470 127 71213 128 204~263 138 701 134 705 144 695 152 687 156 683 347 492 348 491141 698 154 685 353 486 352 487 157 682 153 686 135 704 139 700 143 696345 494 145 694 133 706 344 495 351 488 130 709 128 711 142 697 151 688137 702 355 484 148 691 129 710 140 699 14 158 264~327 168 671 178 661329 510 179 660 339 500 201 638 173 666 187 652 200 639 163 676 166 673175 664 322 517 172 667 184 655 182 657 321 518 333 506 327 512 319 520189 650 171 668 199 860 167 672 158 681 191 648 169 670 186 653 170 669323 516 160 679 330 509 15 202 328~383 220 619 206 633 205 634 225 614218 621 234 605 318 521 313 526 221 618 224 615 311 528 215 624 212 627211 628 308 531 306 533 316 523 228 611 217 6822 203 636 304 536 202 637303 536 236 603 302 537 233 606 305 534 210 629 16 237 384~455 280 559265 574 267 572 266 573 287 552 286 553 242 597 261 578 293 546 288 551268 571 276 563 241 593 255 584 289 550 254 585 300 539 257 582 281 558292 547 294 545 299 540 248 591 250 589 297 542 298 541 275 564 237 602244 595 249 590 247 592 273 566 269 570 272 567 291 548 271 568 High 17237 456~513 259 588 264 575 285 554 283 556 279 560 240 599 258 581 296543 270 569 274 565 252 587 262 577 290 549 256 583 245 594 260 579 253586 263 576 251 588 284 555 282 557 295 544 301 538 243 598 277 562 239600 238 601 278 561 246 593 18 202 514~561 213 626 312 527 314 525 208631 310 529 231 608 204 635 222 617 207 632 307 532 223 616 317 522 216623 227 612 309 530 235 604 209 630 229 610 214 625 315 524 226 613 219620 232 607 230 609 19 158 562~629 177 662 337 502 196 643 328 511 180659 335 504 198 641 324 515 336 503 159 680 181 658 190 649 161 678 331508 165 674 188 651 325 514 197 642 183 656 320 519 193 646 334 505 164675 174 665 340 499 195 644 338 501 332 507 192 647 326 513 194 645 176663 162 677 185 654 20 128 630~659 150 689 350 489 342 497 343 496 341498 354 485 149 690 136 703 346 493 146 693 132 707 155 684 131 708 349490 147 692 21 100 660~707 111 728 126 713 102 737 109 730 363 476 361478 112 727 106 733 360 479 356 483 125 714 122 717 103 736 358 481 110729 117 722 113 726 116 723 100 739 107 732 124 715 365 474 364 475 115724 22 82 708~729 371 468 99 740 98 741 85 754 90 749 86 753 91 748 83756 93 746 376 463 94 745 23 68 730~751 385 454 384 455 72 767 76 763 80759 78 761 379 460 69 770 79 760 382 457 77 762 24 55 752~765 63 776 67772 387 452 57 782 388 451 390 449 386 453 25 46 766~777 52 787 395 44448 791 46 793 47 792 51 788 26 38 778~789 397 442 399 440 44 795 38 80141 798 45 794 27 32 790~795 32 807 36 803 403 436 28 26 796~803 26 81329 810 27 812 31 808 29 22 804~809 407 432 22 817 25 814 30 18 810~815410 429 19 820 18 821 31 15 816~819 16 823 411 428 32 — 820~837 417 42211 828 9 830 3 836 418 421 2 837 416 423 413 426 414 425

Note that in Tables 1 and Table 2, the logic index can start either from1 or 0 in various embodiments. It should also be noted that in Tables 1and 2 it is assumed that pair-wise sequence assignment is employed, thatis, sequence indices u and N_(zc)−u are listed together in pairs. Thepair ordering can be either u and N_(zc)−u, or N_(zc)−u and u, thoughthe former is assumed in all the tables above. In addition, any cyclicshift of sequence ordering as listed in these tables, in eitherclock-wise or counter clock-wise direction, or a one-to-one mapping ofthe provided ordering through a transformation, can be used withoutviolating the sequence ordering rules as agreed in 3GPP R1-074514, “Wayforward proposal on PRACH sequence ordering,” Shanghai, China, Oct.8-12, 2007.

FIG. 14 is a flow diagram illustrating operation of a signaling processfor selecting a preamble configuration for transmission of the preambleof FIG. 3. For a particular cell served by a particular eNB, apre-defined set of sequences is defined 1402 according to one of thevarious schemes described above with respect to FIGS. 5-9. In oneembodiment, all of the cells within a network will use the samepre-defined set of sequences. In other embodiments, various parts of anetwork may use different pre-defined set of sequences. In an embodimentof a large network, the pre-defined set of sequences may span all 839sequences, while in an embodiment of a small network only a portion ofthe entire set may be used.

As described in more detail above, a sequence length of 839 is assumedin the present embodiment which means that ten bits are required tosignal one Zadoff-Chu generating index. Given that up to 64 sequencesmay need to be signaled within one cell, it is highly desirable tominimize the associated overhead due to signaling multiple sequences.This is achieved by signaling 1404 only one logical index from the eNBserving the cell to UE within the cell. The eNB also transmits 1406 oneor more auxiliary parameters to a particular UE that defines whichsequence or set of sequences that UE is to use for transmission.

Each UE then produces 1408 the subsequent sequences according to thepre-defined ordering of sequences. Each ZC sequence has a unique logicalindex. The ordering of sequences is identified by the logical indexes ofthe sequences, with each logical index uniquely mapped to a generatingindex. Depending on its mode of operation, a UE may use from one tosixty four sequences for transmission. For example, suppose a UE hasbeen scheduled by the eNB to use four sequences and the eNB hastransmitted “74” as the indication of the logical index of the firstsequence. The UE then must produce the remaining three sequences byselecting them from an ordered group of sequences using the receivedindication of the logical index of the first sequence and using theauxiliary parameter, wherein the ordered group of sequences is a propersubset of the pre-defined set of sequences.

The UE then produces 1410 a transmission signal that includes thepreamble structure by modulating a designated one of the sequences thatwere assigned to it by the process described above. The transmissionsignal is transmitted to the eNB during an allocated time slot asdescribed in more detail with respect to FIGS. 2-4 and FIG. 15.

FIG. 15 is a block diagram of an illustrative transmitter 600 fortransmitting the preamble structure of FIG. 3. Apparatus 600 comprisesZC Root Sequence Selector 601, Cyclic Shift Selector 602, RepeatSelector 603, ZC Root Sequence Generator 604, Cyclic Shifter 605,Discrete Fourier Transform (DFT) in 606, Tone Map 607, other signals orzero-padding in 611, Inverse Discrete Fourier Transform (IDFT) in 608,Repeater in 609, optional repeated samples 612, Add CP in 610, and thePRACH signal in 613. Elements of the apparatus may be implemented ascomponents in a fixed or programmable processor. In some embodiments,the IDFT block in 608 may be implemented using an Inverse Fast FourierTransform (IFFT), and the DFT block in 606 may be implemented using aFast Fourier Transform (FFT).

Apparatus 600 is used to select and perform the PRACH preamble signaltransmission as follows. As was described in more detail above, apre-defined set of sequences is defined according to one of the variousschemes described above with respect to FIGS. 5-9. An ordered group ofsequences that is a proper subset of the pre-defined set of sequences isused within a particular cell. Upon entering the cell, a UE receives anindication of a logical index for a first sequence, wherein the firstsequence belongs to the ordered group of sequences and an indication ofan auxiliary parameter that further describes the amount of cyclic shiftto use. The UE performs selection of the CAZAC (e.g. ZC) root sequenceusing the ZC root sequence selector module 601 and the selection of thecyclic shift value using the cyclic shift selector module 602. Thesequence is selected from the ordered group of sequences using thereceived indication of the logical index of the first sequence and usingthe auxiliary parameter, as was described in more detail above.

Next, the UE generates the ZC sequence using the ZC root sequencegenerator 604 using the generation index of the selected sequence. Then,if necessary, the UE performs cyclic shifting of the selected ZCsequence using the Cyclic Shifter 605. The UE performs DFT (DiscreteFourier Transform) of the cyclically shifted ZC sequence in DFT 606. Theresult of the DFT operation is mapped onto a designated set of tones(sub-carriers) using the Tone Map 607. Additional signals orzero-padding 611, may or may not be present. The UE next performs IDFTof the mapped signal using the IDFT 608. The size of the IDFT in 608 mayoptionally be larger than the size of DFT in 606.

In other embodiments, the order of cyclic shifter 605, DFT 606, tone map607 and IDFT 608 may be arranged in various combinations. For example,in one embodiment a DFT operation is performed on a selected rootsequence, tone mapping is then performed, an IDFT is performed on themapped tones and then the cyclic shift may be performed. In anotherembodiment, tone mapping is performed on the root sequence and then anIDFT is performed on the mapped tones and then a cyclic shift isperformed.

In this disclosure, the cyclically shifted or phase ramped CAZAC-likesequence is sometimes denoted as cyclic shifted base sequence, cyclicshifted root sequence, phase ramped base sequence, phase ramped rootsequence, or any other equivalent term. In other places, the CAZAC-likesequence is generally referred to as the second sequence.

FIG. 16 is a block diagram illustrating the network system of FIG. 1. Asshown in FIG. 16, the wireless networking system 900 comprises a mobileUE device 901 in communication with an eNB 902. The mobile UE device 901may represent any of a variety of devices such as a server, a desktopcomputer, a laptop computer, a cellular phone, a Personal DigitalAssistant (PDA), a smart phone or other electronic devices. In someembodiments, the electronic mobile UE device 901 communicates with theeNB 902 based on a LTE or E-UTRAN protocol. Alternatively, anothercommunication protocol now known or later developed can be used.

As shown, the mobile UE device 901 comprises a processor 903 coupled toa memory 907 and a Transceiver 904. The memory 907 stores (software)applications 905 for execution by the processor 903. The applications905 could comprise any known or future application useful forindividuals or organizations. As an example, such applications 905 couldbe categorized as operating systems (OS), device drivers, databases,multimedia tools, presentation tools, Internet browsers, e-mailers,Voice-Over-Internet Protocol (VOIP) tools, file browsers, firewalls,instant messaging, finance tools, games, word processors or othercategories. Regardless of the exact nature of the applications 905, atleast some of the applications 905 may direct the mobile UE device 901to transmit UL signals to the eNB (base-station) 902 periodically orcontinuously via the transceiver 904. In at least some embodiments, themobile UE device 901 identifies a Quality of Service (QoS) requirementwhen requesting an uplink resource from the eNB 902. In some cases, theQoS requirement may be implicitly derived by the eNB 902 from the typeof traffic supported by the mobile UE device 901. As an example, VOIPand gaming applications often involve low-latency uplink (UL)transmissions while High Throughput (HTP)/Hypertext TransmissionProtocol (HTTP) traffic can involve high-latency uplink transmissions.

Transceiver 904 includes uplink logic which may be implemented byexecution of instructions that control the operation of the transceiver.Some of these instructions may be stored in memory 907 and executed whenneeded. As would be understood by one of skill in the art, thecomponents of the Uplink Logic may involve the physical (PHY) layerand/or the Media Access Control (MAC) layer of the transceiver 904.Transceiver 904 includes one or more receivers 920 and one or moretransmitters 922. The transmitter(s) may be embodied as described withrespect to FIG. 14. In particular, as described above, in more detail, apre-defined set of sequences is defined according to one of the variousschemes described above with respect to FIGS. 5-9. An ordered group ofsequences that is a proper subset of the pre-defined set of sequences isused within a particular cell. Upon entering the cell, a UE receives anindication of a logical index for a first sequence from eNB 902, whereinthe first sequence belongs to the ordered group of sequences and anindication of an auxiliary parameter that further describes the amountof cyclic shift to use. Transceiver module 904 produces a secondsequence using the received indication of the logical index of the firstsequence and using the auxiliary parameter, by selecting the secondsequence from the ordered group of sequences. Transmitter module 922produces a transmission signal by modulating the second sequence to forma PRACH preamble, as described in more detail above.

As shown in FIG. 16, the eNB 902 comprises a Processor 909 coupled to amemory 913 and a transceiver 910. The memory 913 stores applications 908for execution by the processor 909. The applications 908 could compriseany known or future application useful for managing wirelesscommunications. At least some of the applications 908 may direct thebase-station to manage transmissions to or from the user device 901.

Transceiver 910 comprises an uplink Resource Manager 912, which enablesthe eNB 902 to selectively allocate uplink PUSCH resources to the userdevice 901. As would be understood by one of skill in the art, thecomponents of the uplink resource manager 912 may involve the physical(PHY) layer and/or the Media Access Control (MAC) layer of thetransceiver 910. Transceiver 910 includes a Receiver 911 for receivingtransmissions from various UE within range of the eNB.

Uplink resource manager 912 executes instructions that control theoperation of transceiver 910. Some of these instructions may be locatedin memory 913 and executed when needed. Resource manager 912 controlsthe transmission resources allocated to each UE that is being served byeNB 902 and broadcasts control information via the physical downlinkcontrol channel PDCCH. In particular, eNB 902 selects a second sequenceto be assigned to UE 901 within a cell served by eNB 902 from thepre-defined set of sequences. As was described in more detail above, thesecond sequence is selected from an ordered group of sequences,containing at least a first sequence, that is a proper subset of thepre-defined set of sequences. Transceiver 910 transmits an indication ofa logical index for the first sequence to UE 901 along with anindication of an auxiliary parameter; the auxiliary parameter and theindication of the logical index of the first sequence together identifya logical index of the second sequence. At some later point in time, eNB902 receives a PRACH preamble transmission signal from the UE containinga modulated second sequence.

FIG. 17 is a block diagram of a UE 1000 that stores a fixed set ofpreamble parameter configurations for use across a complete range ofcell sizes within the cellular network, as described above. Digitalsystem 1000 is a representative cell phone that is used by a mobileuser. Digital baseband (DBB) unit 1002 is a digital processing processorsystem that includes embedded memory and security features.

Analog baseband (ABB) unit 1004 performs processing on audio datareceived from stereo audio codec (coder/decoder) 1009. Audio codec 1009receives an audio stream from FM Radio tuner 1008 and sends an audiostream to stereo headset 1016 and/or stereo speakers 1018. In otherembodiments, there may be other sources of an audio stream, such acompact disc (CD) player, a solid state memory module, etc. ABB 1004receives a voice data stream from handset microphone 1013 a and sends avoice data stream to handset mono speaker 1013 b. ABB 1004 also receivesa voice data stream from microphone 1014 a and sends a voice data streamto mono headset 1014 b. Usually, ABB and DBB are separate ICs. In mostembodiments, ABB does not embed a programmable processor core, butperforms processing based on configuration of audio paths, filters,gains, etc being setup by software running on the DBB. In an alternateembodiment, ABB processing is performed on the same processor thatperforms DBB processing. In another embodiment, a separate DSP or othertype of processor performs ABB processing.

RF transceiver 1006 includes a receiver for receiving a stream of codeddata frames and commands from a cellular base station via antenna 1007and a transmitter for transmitting a stream of coded data frames to thecellular base station via antenna 1007. The transmitter may be embodiedas described above in more detail with reference to FIGS. 15-16. Acommand received from the base station indicates what configurationnumber of the fixed set of preamble parameter configurations is to beused in a given cell, as described in more detail above.

A non-synchronous PRACH signal is transmitted using a selected preamblestructure based on cell size when data is ready for transmission asdescribed above. In particular, the PRACH preamble is transmitted bymodulating a sequence that is produced by using a received indication ofa logical index of a first sequence and using an auxiliary parameter,wherein the sequence is selected from an ordered group of sequences, andwherein the ordered group of sequences is a proper subset of apre-defined set of sequences, as described in more detail with respectto FIGS. 2-13 In response, scheduling commands are received from theserving base station. Among the scheduling commands can be a command(implicit or explicit) to use a particular sub-channel for transmissionthat has been selected by the serving NodeB. Transmission of thescheduled resource blocks are performed by the transceiver using thesub-channel designated by the serving NodeB. Frequency hopping may beimplied by using two or more sub-channels as commanded by the servingNodeB. In this embodiment, a single transceiver supports OFDMA andSC-FDMA operation but other embodiments may use multiple transceiversfor different transmission standards. Other embodiments may havetransceivers for a later developed transmission standard withappropriate configuration. RF transceiver 1006 is connected to DBB 1002which provides processing of the frames of encoded data being receivedand transmitted by cell phone 1000.

The basic SC-FDMA DSP radio can include DFT, subcarrier mapping, andIFFT (fast implementation of IDFT) to form a data stream fortransmission and DFT, subcarrier de-mapping and IFFT to recover a datastream from a received signal. DFT, IFFT and subcarriermapping/de-mapping may be performed by instructions stored in memory1012 and executed by DBB 1002 in response to signals received bytransceiver 1006.

DBB unit 1002 may send or receive data to various devices connected toUSB (universal serial bus) port 1026. DBB 1002 is connected to SIM(subscriber identity module) card 1010 and stores and retrievesinformation used for making calls via the cellular system. DBB 1002 isalso connected to memory 1012 that augments the onboard memory and isused for various processing needs. DBB 1002 is connected to Bluetoothbaseband unit 1030 for wireless connection to a microphone 1032 a andheadset 1032 b for sending and receiving voice data.

DBB 1002 is also connected to display 1020 and sends information to itfor interaction with a user of cell phone 1000 during a call process.Display 1020 may also display pictures received from the cellularnetwork, from a local camera 1026, or from other sources such as USB1026.

DBB 1002 may also send a video stream to display 1020 that is receivedfrom various sources such as the cellular network via RF transceiver1006 or camera 1026. DBB 1002 may also send a video stream to anexternal video display unit via encoder 1022 over composite outputterminal 1024. Encoder 1022 provides encoding according toPAL/SECAM/NTSC video standards.

As used herein, the terms “applied,” “coupled,” “connected,” and“connection” mean electrically connected, including where additionalelements may be in the electrical connection path. “Associated” means acontrolling relationship, such as a memory resource that is controlledby an associated port. The terms assert, assertion, de-assert,de-assertion, negate and negation are used to avoid confusion whendealing with a mixture of active high and active low signals. Assert andassertion are used to indicate that a signal is rendered active, orlogically true. De-assert, de-assertion, negate, and negation are usedto indicate that a signal is rendered inactive, or logically false.

While the invention has been described with reference to illustrativeembodiments, this description is not intended to be construed in alimiting sense. Various other embodiments of the invention will beapparent to persons skilled in the art upon reference to thisdescription.

Embodiments of this invention apply to any flavor of frequency divisionmultiplex based transmission. Thus, the concept of valid specificationof sub-channels can easily be applied to: OFDMA, OFDM, DFT-spread OFDM,DFT-spread OFDMA, SC-OFDM, SC-OFDMA, MC-CDMA, and all other FDM-basedtransmission strategies.

A NodeB is generally a fixed station and may also be called a basetransceiver system (BTS), an access point, or some other terminology. AUE, also commonly referred to as terminal or mobile station, may befixed or mobile and may be a wireless device, a cellular phone, apersonal digital assistant (PDA), a wireless modem card, and so on.

In a general embodiment of the present disclosure, the set of allowedPRACH preamble signals is defined by two other sets: 1) a set of allowedroot CAZAC sequences, and 2) a set of allowed modifications to a givenroot CAZAC sequence. In one embodiment, PRACH preamble signal isconstructed from a CAZAC sequence, such as a ZC sequence. Additionalmodifications to the selected CAZAC sequence can be performed using anyof the following operations: multiplication by a complex constant, DFT,IDFT, FFT, IFFT, cyclic shifting, zero-padding, sequenceblock-repetition, sequence truncation, sequence cyclic-extension, andothers. Thus, in various embodiments of the present disclosure, a UEconstructs a PRACH preamble signal by selecting a CAZAC sequence,possibly applying a combination of the described modifications to theselected CAZAC sequence, modulating the modified sequence, andtransmitting the resulting PRACH signal over the air.

In some embodiments, the fixed set of preamble parameters stores boththe cyclic shift values and the number of root sequences, while in otherembodiments the cyclic shift values are stored and the number of rootsequences is computed from the cyclic shift values.

It is therefore contemplated that the appended claims will cover anysuch modifications of the embodiments as fall within the true scope andspirit of the invention.

What is claimed is:
 1. Method for communicating, comprising: receivingat a user equipment an indication of a logical index for a firstsequence, wherein the first sequence belongs to a pre-defined set ofsequences; receiving at a user equipment an indication of an auxiliaryparameter, wherein the auxiliary parameter indicates whether currentcell is a high speed cell or not; producing a second sequence using thereceived indication of the logical index of the first sequence and usingthe auxiliary parameter, wherein the second sequence is a CyclicallyShifted Zadoff-Chu(CS-ZC) sequence selected from an ordered group ofsequences, and wherein the ordered group of sequences is a proper subsetof the pre-defined set of sequences; and producing a transmission signalby modulating the second sequence.
 2. Method of claim 1, wherein thesecond sequence has a logical index and a generating index; wherein thelogical index indicates a position of a sequence within the orderedgroup; and wherein producing a second sequence comprises: determiningthe generating index of the second sequence; and producing the secondsequence by using said generating index.
 3. Method of claim 2, whereindetermining the generating index of the second sequence comprises:selecting a logical index for the second sequence from a set of logicalindex candidates, wherein the set of logical index candidates isdetermined by the auxiliary parameter and by the logical index of thefirst sequence; and producing the generating index of the secondsequence from its logical index.
 4. Method of claim 1, wherein thesecond sequence has a logical index; and wherein the logical index ofthe second sequence indicates a position of the second sequence withinthe ordered group; and wherein producing the second sequence comprises:retrieving the second sequence stored locally using the logical index ofthe second sequence, wherein the logical index of the second sequence isselected from a set of logical index candidates, and wherein the set oflogical index candidates is determined by the auxiliary parameter and bythe logical index of the first sequence.
 5. Method of claim 1, wherein aprimary metric and a secondary metric are defined for each sequence inthe set; wherein there are exactly 2M ordered groups of sequences;wherein M is an integer; wherein N(1), N(2), . . . , N(2M) are integers;wherein each K-th group comprises sequences with logical indexes Lwherein K and L are nonnegative integers which satisfy N(K)≦L≦N(K+1)−1;wherein the primary metric is a monotonically decreasing function of Lwithin the K-th group whenever K is odd and K≦M; wherein the primarymetric is a monotonically decreasing function of L within the K-th groupwhenever K is even and K>M; wherein the primary metric is amonotonically increasing function of L within the K-th group whenever Kis even and K≦M; wherein the primary metric is a monotonicallyincreasing function of L within the K-th group whenever K is odd andK>M.
 6. Method of claim 5, wherein the primary metric is a cubic metric(CM); wherein the primary metric is no greater than a threshold valuefor the K-th group with K≦M; and wherein the primary metric is greaterthan the threshold value for the K-th group with K>M; and wherein thethreshold value is 1.2 dB.
 7. Method of claim 5, wherein N_(cs)(1),N_(cs)(2),. . . ,N_(cs)(2M+1) are integers; wherein the secondary metricfor each sequence in the K-th group belongs inside an interval[N_(cs)(K), N_(cs)(K+1)] for 1≦K≦M and the interval [N_(cs)CK+1),N_(cs)(K] for M+1≦K≦2M; wherein for K≦M said intervals satisfyN_(cs)(K)<N_(cs)(K+1); wherein for K>M said intervals satisfy N_(cs)(K)>N_(cs) (K+1); and wherein N_(cs)(K)=N_(cs)(2M+2−K).
 8. Method ofclaim 7, wherein the set of sequences comprises Zadoff-Chu (ZC)sequences; wherein each sequence has a length N_(zc); wherein each ZCsequence has a unique generating index u; wherein the secondary metricfor a sequence with generating index u is min(x, N_(zc)−x, |N_(zc)−2x |)wherein x is the unique integer x for which xu mod H_(zc)−1; and wherein|N_(zc)−2x |is the absolute value of N_(zc)−2x.
 9. Method of claim 5,wherein the 2M groups are indexed and sequentially concatenated toproduce the pre-defined set of sequences ordered by their logicalindexes.
 10. Method of claim 1, wherein producing a transmission signalcomprises: performing an N-point discrete Fourier transform (LEFT) onthe second sequence, wherein N is the length of the sequence; mappingthe transformed sequence to a set of N sub-carriers to produce a mappedsequence, wherein N is a positive integer; and performing an Inversediscrete Fourier transform (IDFT) on the mapped sequence to produce atime-domain signal for transmission.
 11. Method of claim 1, whereinproducing a transmission signal comprises: mapping the second sequenceto a set of N sub-carriers, wherein N is a positive integer; andperforming an inverse discrete Fourier transform (IDFT) on the mappedsequence to produce a time-domain signal for transmission.
 12. Method ofclaim 10, further comprising: up-sampling the time-domain signal to aspecific sampling rate; filtering the up-sampled signal with a low-passfilter; and frequency shifting the filtered signal to a specificfrequency location for transmission.
 13. Method of claim 11, furthercomprising: up-sampling the time-domain signal to a specific samplingrate; filtering the up-sampled signal with a low-pass filter; andfrequency shifting the filtered signal to a specific frequency locationfor transmission.
 14. Method of claim 1, wherein there is exactly oneordered group of Zadoff-Chu (ZC) sequences; wherein each ZC sequence hasa generating index; wherein ordering is made by mapping the generatingindexes sequentially to consecutive logical indexes such that a cubicmetric (CM) of each ZC sequence is a monotonic function of the logicalindexes.
 15. Method of claim 1, wherein there is exactly one orderedgroup of Zadoff-Chu (ZC) sequences; wherein each ZC sequence has agenerating index; wherein ordering is made by mapping the generatingindexes {1, N_(zc)−1, 2, N_(zc)−2, 3, N_(zc)−3,. . . ,(N_(zc) −1)/2,(N_(zc)+1)/2}sequentially to consecutive logical indexes; and whereinN_(zc) is the ZC sequence length of a prime number.
 16. An apparatus fortransmitting in a wireless network, comprising: memory circuitrycontaining at least a portion of a pre-defined set of generating indexesof Zadoff-Chu (ZC) sequences, wherein the pre-defined set of generatingindexes are arranged in ordered groups and mapped sequentially to a setof consecutive logical indexes; receiving circuitry operable to receivean indication of a logical index for a first sequence, wherein thelogical index of the first sequence belongs to the set of consecutivelogical indexes, and further operable to receive an indication of anauxiliary parameter, wherein the auxiliary parameter indicates whethercurrent cell is a high speed cell or not; producing circuitry coupled tothe memory circuitry and to the receiving circuitry operable to producea second sequence; wherein the second sequence is a Cyclically ShiftedZadoff-Chu (CS-ZC) sequence produced from a generating index selectedfrom the set of generating indexes in the memory circuitry using theindication of the logical index of the first sequence and using theauxiliary parameter; and transmission circuitry coupled to the producingcircuitry operable to produce a transmission signal by modulating thesecond sequence.
 17. Method for transmission of sequences in wirelessnetworks, comprising: selecting a second sequence to he assigned to auser equipment (UE) within a cell served by a base station (eNB),wherein the second sequence belongs to a pre-defined set of sequences,wherein the second sequence is a Cyclically Shifted Zadoff-Chu (CS-ZC)sequence selected from an ordered group of sequences containing at leasta first sequence, and wherein the ordered group of sequences is a propersubset of the pre-defined set of sequences; transmitting from the eNB anindication of a logical index for the first sequence; transmitting fromthe eNB an indication of an auxiliary parameter indicates whethercurrent cell is a high speed cell or not, wherein the auxiliaryparameter and the indication of the logical index of the first sequencetogether identify a logical index of the second sequence; and receivingat the eNB a transmission signal from the UE containing a modulatedsecond sequence.
 18. An apparatus for communicating in a wirelessnetwork, comprising: circuitry for receiving at a user equipment anindication of a logical index for a first sequence, wherein the firstsequence belongs to a pre-defined set of sequences; circuitry forreceiving at the user equipment an indication of an auxiliary parameter,wherein the auxiliary parameter indicates whether current cell is a highspeed cell or not; circuitry for producing a second sequence using thereceived indication of the logical index of the first sequence and usingthe auxiliary parameter, wherein the second sequence is a CyclicallyShifted Zadoff-Chu (CS-ZC) sequence selected from an ordered group ofsequences, and wherein the ordered group of sequences is a proper subsetof the pre-defined set of sequences; and circuitry for producing atransmission signal by modulating the second sequence.
 19. A method fortransmitting in a wireless network, comprising: arranging a pre-definedset of generating indexes into ordered groups; mapping the orderedgroups of generating indexes sequentially to a set of consecutivelogical indexes; receiving an indication of a logical index for a firstsequence, wherein the logical index of the first sequence belongs to theset of consecutive logical indexes, and further operable to receive anindication of an auxiliary parameter, wherein the auxiliary parameterindicates whether current cell is a high speed cell or not; producing asecond sequence, wherein the second sequence is a Cyclically ShiftedZadoff-Chu (CS-ZC) sequence produced from a generating Index selectedfrom the set of generating indexes in the memory circuitry using theindication of the logical index of the first sequence and using theauxiliary parameter; and producing a transmission signal by modulatingthe second sequence.
 20. An apparatus for communicating in a wirelessnetwork, comprising: circuitry for selecting a second sequence to theassigned to a user equipment (UE) within a cell served by a base station(eNB), wherein the second sequence belongs to a pre-defined set ofsequences, wherein the second sequence is a Cyclically ShiftedZadoff-Chu (CS-ZC) sequence selected from an ordered group of sequencescontaining at least a first sequence, and wherein the ordered group ofsequences is a proper subset of the pre-defined set of sequences;circuitry for transmitting from the eNB an indication of a logical indexfor the first sequence; circuitry for transmitting from the eNB anindication of an auxiliary parameter indicates whether current cell is ahigh speed cell or not, wherein the auxiliary parameter and theindication of the logical index of the first sequence together identifya logical index of the second sequence; and circuitry for receiving atthe eNB a transmission signal from the UE containing a modulated secondsequence.